1. Field of the Invention
The present invention relates to an ink fountain for rotary offset printing units with an ink dosing device which includes a plurality of zone-width dosing elements located next to one another in close proximity. The dosing elements have support and dosing areas, the support areas of which are in constant direct or indirect contact under spring pressure with an ink fountain roller. The dosing areas can be adjusted to different ink gap thicknesses by rotating the dosing elements.
2. Background Information
U.S. Pat. No. 4,387,648, which corresponds to German Patent No. 29 23 678 C2, discloses a similar configuration of an ink fountain, the purpose of which is to prevent the origin of uninked strips on the ink fountain roller as a result of the continuous contact of the support areas. For this purpose, corresponding to each dosing element there is a dosing blade which extends over the length of the dosing element. The purpose of this dosing blade is to spread the ink out axially toward or after the dosing area, so that the ink is distributed evenly over the entire width of the zone. In this known solution, the dosing elements are under a constant spring pressure which, during the operation of the press, i.e. during the rotation of the ink fountain roller, can result in wear and abrasion of the film which covers the dosing elements. In this case, the spring pressure must be designed so that it overcomes the hydrodynamic pressure caused by the rotational movement of the ink fountain roller and guarantees a secure direct or indirect contact between the dosing elements and the cylindrical surface of the ink fountain roller.